1. Field of the Invention
The present invention relates to a method of successively grinding a plurality of cams on a camshaft which, while being rotated about its axis, is rocked about a pivot axis parallel to the camshaft axis in such a manner as to follow one of master cams which is allocated to one of the cams in alignment with a grinding wheel.
2. Description of the Prior Art
Generally, in cam profile grinding, each cam on a camshaft is ground with the camshaft being rotated and being rocked following one of master cams allocated thereto. Once the camshaft is set up on a chucking device of a cam grinder, any of the cams is automatically subjected first to a rough grinding and then to a finish grinding.
As a known cam grinding method of this kind, there has been used a so-called two-series step grinding method for successively grinding all of the cams of a camshaft. In each of first series steps, a rough grinding cycle using a grinding wheel roughly dressed is performed on each cam after the same is aligned with the grinding wheel through axial indexing movement of the camshaft. The first series steps are followed by second series steps, in each of which a finish grinding cycle using the grinding wheel finely dressed is performed on each cam after the same is aligned with the grinding wheel through axial indexing movement of the camshaft.
In this known method, since a dressing is effected on the grinding wheel in advance of the second series steps, the grinding efficiency in each rough grinding step may be heightened at the cost of the damage which is caused on the grinding wheel in the first or rough grinding series steps. However, the known method requires one to repeat twice a series of the axial indexing movements which corresponds in number to the cams of the camshaft. This disadvantageously causes a long period of time to be taken for such axial indexing movements of the camshaft, thereby making it difficult to shorten the total cycle time required for each camshaft.
In order to shorten the total cycle time, it is effective to perform rough and finish grinding steps successively on each cam so that all of cams on a camshaft can be finished through one series of indexing movements of the camshaft. In this case, how to diminish the damage which is caused on the grinding wheel in the rough grinding step is the key point to improvements in the surface roughness and the profile accuracy of each cam.